I analyze the trimethylsilylated bio- mixes with GCMS and DB5ms J&W column. Several unpolar samples were analyzed. After that all mass-spectra of trimethylsilyl derivatives have extremely high m/z73 peak, the spectra of substances of unpolar nature as alkanes remains unchanged. At the temperature of 300C the column bleeds with m/z73. New column doesn't show this problem. Has anybody seen such effect? Can I restore the perfomance of the old column? (dichlormethane, methanol and pentane didn't help)
By Anonymous on Tuesday, September 17, 2002 - 09:11 am:
Trimethylsilyl derivatives typically show m/z of 73 (a good sign that the peak being looked at is a trimethylsilyl derivative); non-derivatized peaks appear normally. We've been using trimethylsilyl derivatives A LOT on GCMS for last dozen years, don't have any residual m/z 73 problems (remember to run TMS injection first, or discard first, to clean out the column as non-volatile polar stuff on the column will get derivatized by the first injection, then elute.
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